[syzbot] [bpf?] general protection fault in bpf_struct_ops_find_value

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: d47b9f68d289 libbpf: Correct bpf_core_read.h comment wrt b..
git tree: bpf-next
console+strace: https://syzkaller.appspot.com/x/log.txt?x=11479fe7e80000
kernel config: https://syzkaller.appspot.com/x/.config?x=719e6acaf392d56b
dashboard link: https://syzkaller.appspot.com/bug?extid=88f0aafe5f950d7489d7
compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=14ea6be3e80000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15bc199be80000

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/1a9b4a5622fb/disk-d47b9f68.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/dd68baeac4fd/vmlinux-d47b9f68.xz
kernel image: https://storage.googleapis.com/syzbot-assets/811ba9dc9ddf/bzImage-d47b9f68.xz

The issue was bisected to:

commit fcc2c1fb0651477c8ed78a3a293c175ccd70697a
Author: Kui-Feng Lee <think...@gmail.com>
Date: Fri Jan 19 22:49:59 2024 +0000

bpf: pass attached BTF to the bpf_struct_ops subsystem

bisection log: https://syzkaller.appspot.com/x/bisect.txt?x=106a04c3e80000
final oops: https://syzkaller.appspot.com/x/report.txt?x=126a04c3e80000
console output: https://syzkaller.appspot.com/x/log.txt?x=146a04c3e80000

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+88f0aa...@syzkaller.appspotmail.com
Fixes: fcc2c1fb0651 ("bpf: pass attached BTF to the bpf_struct_ops subsystem")

general protection fault, probably for non-canonical address 0xdffffc0000000011: 0000 [#1] PREEMPT SMP KASAN
KASAN: null-ptr-deref in range [0x0000000000000088-0x000000000000008f]
CPU: 0 PID: 5058 Comm: syz-executor257 Not tainted 6.7.0-syzkaller-12348-gd47b9f68d289 #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 11/17/2023
RIP: 0010:bpf_struct_ops_find_value+0x49/0x140 kernel/bpf/btf.c:8763
Code: 7d ea dd ff 45 85 e4 0f 84 d7 00 00 00 e8 ff ee dd ff 48 8d bb 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 dc 00 00 00 48 8b 9b 88 00 00 00 48 85 db 0f 84
RSP: 0018:ffffc90003bb7b20 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81aa3283
RDX: 0000000000000011 RSI: ffffffff81aa3291 RDI: 0000000000000088
RBP: ffffc90003bb7dd0 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000002
R13: 000000000000001a R14: ffffffff8ad6bca0 R15: ffffc90003bb7e04
FS: 0000555556ed2380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000160d398 CR3: 000000007809c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
<TASK>
bpf_struct_ops_map_alloc+0x12f/0x5d0 kernel/bpf/bpf_struct_ops.c:674
map_create+0x548/0x1b90 kernel/bpf/syscall.c:1237
__sys_bpf+0xa32/0x4a00 kernel/bpf/syscall.c:5445
__do_sys_bpf kernel/bpf/syscall.c:5567 [inline]
__se_sys_bpf kernel/bpf/syscall.c:5565 [inline]
__x64_sys_bpf+0x78/0xc0 kernel/bpf/syscall.c:5565
do_syscall_x64 arch/x86/entry/common.c:52 [inline]
do_syscall_64+0xd3/0x250 arch/x86/entry/common.c:83
entry_SYSCALL_64_after_hwframe+0x63/0x6b
RIP: 0033:0x7f9f205ef2e9
Code: 48 83 c4 28 c3 e8 37 17 00 00 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 b8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fffa4ce4088 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007fffa4ce4268 RCX: 00007f9f205ef2e9
RDX: 0000000000000048 RSI: 00000000200004c0 RDI: 0000000000000000
RBP: 00007f9f20662610 R08: 0000000000000000 R09: 0000000000000000
R10: 00000000ffffffff R11: 0000000000000246 R12: 0000000000000001
R13: 00007fffa4ce4258 R14: 0000000000000001 R15: 0000000000000001
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:bpf_struct_ops_find_value+0x49/0x140 kernel/bpf/btf.c:8763
Code: 7d ea dd ff 45 85 e4 0f 84 d7 00 00 00 e8 ff ee dd ff 48 8d bb 88 00 00 00 48 b8 00 00 00 00 00 fc ff df 48 89 fa 48 c1 ea 03 <80> 3c 02 00 0f 85 dc 00 00 00 48 8b 9b 88 00 00 00 48 85 db 0f 84
RSP: 0018:ffffc90003bb7b20 EFLAGS: 00010206
RAX: dffffc0000000000 RBX: 0000000000000000 RCX: ffffffff81aa3283
RDX: 0000000000000011 RSI: ffffffff81aa3291 RDI: 0000000000000088
RBP: ffffc90003bb7dd0 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000000000002 R11: 0000000000000000 R12: 0000000000000002
R13: 000000000000001a R14: ffffffff8ad6bca0 R15: ffffc90003bb7e04
FS: 0000555556ed2380(0000) GS:ffff8880b9800000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 000000000160d398 CR3: 000000007809c000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
----------------
Code disassembly (best guess), 4 bytes skipped:
0: 45 85 e4 test %r12d,%r12d
3: 0f 84 d7 00 00 00 je 0xe0
9: e8 ff ee dd ff call 0xffddef0d
e: 48 8d bb 88 00 00 00 lea 0x88(%rbx),%rdi
15: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
1c: fc ff df
1f: 48 89 fa mov %rdi,%rdx
22: 48 c1 ea 03 shr $0x3,%rdx
* 26: 80 3c 02 00 cmpb $0x0,(%rdx,%rax,1) <-- trapping instruction
2a: 0f 85 dc 00 00 00 jne 0x10c
30: 48 8b 9b 88 00 00 00 mov 0x88(%rbx),%rbx
37: 48 85 db test %rbx,%rbx
3a: 0f .byte 0xf
3b: 84 .byte 0x84


---
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[Martin KaFai Lau]

The check should be IS_ERR_"OR_NULL"(btf). Kui-Feng, please take a look. Thanks.

[Kui-Feng Lee]

Sure!